The project is part of a general program to study the chemical basis and biosynthetic origin of native neurophysin conformation and its association with neuropeptide hormone. Native neurophysin modified chemically or enzymatically has been probed for native conformation and the ability to bind hormone using specific antibodies and affinity chromatography. Neurophysin biosynthetic precursors have been obtained by in vitro protein synthesis and probed in the same way. The assignment of disulfides in neurophysin has been attempted in preparation for a study of neurophysin precursor folding. The purification of neurophysin mRNA for efficient translation in vitro has led to the elucidation of several aspects of neurophysin biosynthesis. A project has been initiated to isolate proteases from hypothalamic and posterior pituitary tissue which act in the processing neurophysin biosynthetic precursors.